The present invention relates to surface cleaning equipment. More particularly the present invention relates to a novel mechanical coupling for retaining a wiper assembly to a surface maintenance vehicle that preserves the wiper assembly from damage in event of contact with oversize debris, a stationary object or other impediments and obstacles which create significant resistance to the desired motion of the wiper assembly.
Surface maintenance vehicles and cleaning devices have a long history subject to gradual innovation and improvement toward improved and oftentimes automated performance in removing debris and contamination from floors. These vehicles and devices may be self-powered, towed, or pushed, and/or manually powered and may carry a human operator during cleaning operations. Such vehicles and devices include scrubbers, extractors, sweepers and vacuums, as well as combinations thereof, intended for cleaning, scrubbing, wiping and/or drying a portion of a substantially flat surface both indoors and outdoors. Many such vehicles and devices employ a squeegee assembly for wiping dry a floor which has been cleaned by application of a cleaning solution of water and a detergent in conjunction with scrubbing action of one or more moving brushes. Accordingly, the squeegee assembly of such prior art cleaning vehicles often mounts at or near the rear of the surface maintenance vehicle to direct the solution to a removal location where the solution (including suspended dirt, particles and contaminants) is removed. In this disclosure, the term xe2x80x9cloaded cleaning solutionxe2x80x9d shall apply to such a cleaning solution after application thereof to a floor or other surface to be cleaned. The cleaning solution is typically supplied to the floor surface through or near rotary scrub brushes operating from a lower portion of the vehicle. The squeegee assembly may include a squeegee supporting member of generally arcuate configuration with two squeegee blades spaced apart and affixed to the supporting member to promote consistent contact with the surface to be cleaned and wiped.
In some prior art cleaning vehicles having two squeegee blades, a vacuum source may couple to the wiping assembly to lift the loaded cleaning solution from the space between the blades to a remote reservoir or other collection unit. The squeegee assembly is often sufficiently wide to at least fully cover the path width of the scrub brushes and/or the wheels of the cleaning vehicle. Consequently, at least the ends of the squeegee assembly tend to be exposed at the sides of the vehicle and are therefore potentially very vulnerable to contact with stationary objects which might be encountered during operation of the vehicle during cleaning operations and when transporting the vehicle between cleaning operations. Solid contact between an end of a squeegee assembly and a stationary object such as, for example, a vertical support column, can result in substantial and costly damage to not only the squeegee assembly but also the surface maintenance vehicle itself resulting in downtime, costly repair and/or replacement of all or a part of the vehicle (as well as the stationary object) and in some circumstances causing damage or injury to the human operator of the vehicle as well.
Releasable squeegee assembly structures for cleaning vehicles and devices have been known in the art, such as that disclosed in U.S. Pat. No. 4,363,152 issued Dec. 14, 1982 to Karpanty. In this prior art reference, a squeegee assembly includes a squeegee-bearing mounting plate having threaded bolts mechanically connected via conventional wing nuts to rear-facing open-ended slots extending from a cleaning vehicle. The resulting metal-on-metal contact between the bolts, slots and nuts provides a so-called xe2x80x9cfriction fitxe2x80x9d attachment with a frictional force magnitude depending on the degree of tightening of the individual wing nuts. In the event the squeegee assembly collides with an unmovable obstacle, presumably each nut and bolt pair moves out of, and disconnects from, its respective slot at some discrete, albeit somewhat arbitrary, level of imparted force. If the nut is in fact overly tight, the release mechanism will not provide for the squeegee to disengage unless and until such level of force reaches said arbitrary level of imparted force, regardless of: (i) the amount of contact time between the squeegee and the obstacle; (ii) the degree of damage incurred by the squeegee; (iii) the elasticity of the collision between the squeegee and the obstacle; and, (iv) the amount of damage incurred by the obstacle. Conversely, if the nut is in fact overly loose, the release mechanism will provide for the squeegee to disengage repeatedly without apparent or desired reason.
Accordingly, the just recited prior art approach and other known assemblies rely on a frictional force developed between opposing metallic surfaces. Unfortunately, as in the reference immediately above, the frictional force is fully dependent upon the degree of manual tightening of a knob or wing nut. One limitation of these known squeegee assembly release structures is that the release force is variable and dependent upon the degree of manual tightening and resulting friction developed between the opposed metallic surfaces.
As stated above, over-tightening may effectively prevent release of the assembly with resulting damage and loss to the cleaning vehicle, the facility being cleaned and even the operator of the vehicle. Inadequate tightening may result in repeated, premature release of the assembly with associated costly downtime, re-cleaning, and re-attachment (again without calibration or other measures to ensure adequate tightening). In addition, when more than one such attachment location must be addressed and suitable mechanically coupled, the possibility of un-even tightening becomes a probability with costly implications similar to those cited above.
The present invention teaches, enables and discloses an improved mechanical coupling for a wiper assembly usable in a surface maintenance vehicle. Such a vehicle includes those self-powered and manually powered cleaning vehicles applied to the task of removing loaded cleaning solution from a cleaned surface and preferably include all such vehicles using an articulated wiper assembly; although rigid or fixed wiper assemblies for such vehicles benefit from the teaching of this disclosure. Such a surface may comprise an interior or exterior floor having some limited porosity but preferably comprising finished concrete (whether painted or sealed), asphalt, ceramic tile, resin-based tile, and the like and including most types of flooring typical of commercial and industrial-grade facilities. However, the teaching hereof finds application in diverse handling of fluids, whether or not xe2x80x9cloaded,xe2x80x9d naturally-occurring liquid(s) or pure cleaning fluid.
Accordingly, the articulated wiper assembly of the present invention tolerates a wide variety of stresses imparted to the blade portions of a wiper assembly during wiping operations and before becoming temporarily disconnected from a surface maintenance vehicle to which it is coupled. In most embodiments of the present invention, the wiper assembly couples to a mounting plate member coupled to the maintenance vehicle and typically designed to permit the wiper assembly to articulate, or xe2x80x9cfloat,xe2x80x9d thereby maintaining contact between one or more wiper blades secured to the wiper assembly and a portion of the surface to be cleaned during operation of the surface maintenance vehicle. An articulated wiper assembly utilizing the teaching of the present invention thus may be raised, lowered, pivoted and/or rotated either passively using gravity or manually using gearing, cables and the like and/or via internal combustion, electric, pneumatic, hydraulic or other motive means.
The improved mechanical coupling of the present invention by using a deformable member adds a modicum of additional travel, while not increasing the degree of mechanical freedom of existing articulated wiper assemblies in response to stress forces imparted to a wiper assembly. Accordingly, the teaching of the present invention may be applied to previously manufactured surface maintenance equipment and vehicles, in the form of retrofitted mechanical couplings, requiring modest engineering and installation efforts.
While not required to practice the present invention, in one preferred embodiment of the present invention at least two wiper blades are both secured to a mounting plate which forms a substantially sealed chamber when biased toward the surface to be cleaned. A source of vacuum is applied to a port formed in a side of the sealed chamber to evacuate the loaded liquid and the like from the sealed chamber to a storage vessel or reservoir in anticipation of later disposal.
During cleaning operations, as the maintenance vehicle is propelled forward over a portion of a surface to be cleaned, when the articulated wiper assembly contacts a relatively stationary object, or otherwise becomes subject to instantaneous or very rapidly increasing resistance to forward movement, the improved mechanical coupling for the articulated wiper assembly initially absorbs some of the stresses imparted to the wiper assembly. Typically, portions of each improved mechanical coupling designed to absorb the stress forces will deform most nearest the location of increasing resistance to forward movement, and may either become fully disconnected if the stress force reaches a threshold force value or recoil to the original mounting location after absorbing forces that are less than said threshold force value. The threshold value force at which a wiper assembly dislodges from its mounting location is designed to avoid damage to the wiper assembly, the articulated mounting member (if any), and the maintenance vehicle itself. The threshold force value may vary but due to the design of the improved mechanical coupling of the present invention, said threshold force value should have a substantially similar magnitude independent of the axial compressive force applied each time the mechanical coupling attaches a wiper assembly to a maintenance vehicle.
A further advantage of the improved mechanical coupling provided herein is that the wiper members and the entire wiper assembly is permitted a slight range of motion in both a select vertical dimension, or set of vertically-oriented axes, and in a horizontal dimension, or set of horizontally-oriented planes. In effect, the present invention adds a small but useful range of three dimensional motion to the parts thus coupled together, albeit composed in majority of both vertical and horizontal components of motion, so that during cleaning operations the wiper assembly is not fully constrained only to the range of motion provided by the articulated mounting location but has a second, substantially independent range of motion due to the improved mechanical coupling of the present invention. The second, substantially independent range and precision of motion provides mechanical tolerance to discrete instantaneous forces affecting the wiper assembly so that the wiper blades exhibit an increased effectiveness in response to contact with diverse size obstacles present on, and obstacles adjacent to, a surface to be cleaned.
In a preferred form, the improved mechanical coupling comprises a resilient, deformable member, capable of absorbing stress primarily in a horizontal plane opposing to a forward direction of travel for the maintenance vehicle. The deformable member is preferably shaped like a round washer member having a substantially common-radius central aperture, or passageway, and an enlarged head feature of increased outer radius on one end thereof. The deformable washer member is also preferably biased to support the enlarged head feature on an upper side of a mounting location at all times regardless whether or not the wiper assembly is coupled thereto.
In addition, in combination with the deformable washer member (and biasing feature for ease of mounting and remounting same) a substantially non-deformable central sleeve member resides within the common-radius central aperture thereof to limit the deformation of the deformable washer member, thereby functioning as a mechanical xe2x80x9ctravel stopxe2x80x9dfeature, and thus creating a fairly uniform and limited range of compressive force for the entire assembly when operatively coupled to a maintenance vehicle. Of course, a variety of different components may be substituted for the central sleeve member as a travel stop such as a rigid pin or set of such pins or irregularly shaped members embedded in, or disposed adjacent to, the deformable washer member will suffice to limit the amount of compression-induced deformation of the deformable washer member. Thus, the deformable, resilient coupling may include a relatively rigid stop element, such as a sleeve member formed of material designed to withstand deformation in an axial direction, through which a preferably threaded shank is received during assembly. The metal sleeve operatively limits the degree of deformation of the deformable, resilient coupling portion during assembly.
Those of skill in the art will recognize that various other structure may serve in lieu of the functionality provided by a compressive fastener such as a threaded shank. For example, a cam-actuated structure, a rachet-type rotary structure, a stepper or servo motor driving any of the aforesaid or similar structure in conjunction with suitable gearing, belts, shafts in conjunction with force or power conducting technologies, including pneumatic, hydraulic, piezoelectric, and electrical and using suitable conduit and coupling may be used in practicing the invention.
In a most preferred embodiment, additional mechanical biasing of the washer member is provided by a biasing structure inserted into the interior of the central sleeve member designed to support the deformable washer in a desired pre-mount configuration. This additional mechanical biasing is provided by a series of at least about four inwardly directed radial teeth, or protrusions, formed of urethane, or similar material and designed to grip a central threaded shank member and hold the entire mechanical coupling together in place adjacent a mounting location for the wiper assembly.
The mounting location preferably comprises a set of two or more open-ended discrete collar-shaped, or generally semi-circular, mounts having an open channel formed opposite the direction of travel of the maintenance vehicle. The open-ended mounts may be ovoid, toroidal, annular, or even rectangular-shaped mounts, and the like as long as the open channel, or spacing, is provided therein so that the improved mechanical coupling may exit thereof when a threshold value force impacts the wiper assembly.
In another embodiment of the present invention, a tapered bore having a bore axis formed in a structural member of an attachment member substantially parallel to the direction of travel of the cleaning vehicle has a narrow end of said tapered bore facing an assembly to be coupled thereto. The tapered bore is adapted to receive a similarly shaped resilient, deformable stopple member, or plug. The stopple member is connected to remote structure separate from the opposing tapered bore formed in the structural member. The stopple member may be provided with a source of local compression along the bore axis so that the stopple member expands to frictionally seat more firmly into the tapered bore. In an alternative embodiment hereof, the tapered bore may extend vertically through the structural member so that the stopple member may be simply dropped, or slipped, down into the vertically extending tapered bore to complete the resilient, deformable coupling between the structural member and the remote structure.
In general, the improved mechanical coupling of the present invention comprises subcomponents shaped to cooperate with other subcomponents and not limited to type of motive force applied although all elements of the improved mechanical coupling are preferably tightened, and loosened, manually.
One object of the invention is to provide an articulated wiper assembly for a surface maintenance vehicle which is tolerant of stress forces imparted to the wiper assembly and designed to progressively begin to separate from the vehicle as cumulative stresses upon the articulated wiper assembly from a physical obstacle, such as a stationary object, grow toward a threshold force value.
Another object of the present invention is to provide an articulated wiper assembly for a surface maintenance vehicle which is releasably connected to the vehicle via one or more deformable, resilient mechanical coupling members having a pre-selected release mode intended to preserve in good working order the components of the articulated wiper assembly, the surface maintenance vehicle, and the physical obstacle encountered by the wiper assembly as well as the operator of the vehicle.
Another object of the present invention is to teach, enable and disclose a class of mechanical coupling assemblies useable for connecting an articulated wiper assembly to a surface maintenance vehicle having a predetermined release force threshold which is generally the same for each of a plurality of such coupling assemblies and is substantially independent of the degree of compressive stress imparted to the mechanical coupling when first connected.
These and other objects, features and advantages will become apparent in light of the following detailed description of the preferred embodiments in connection with the drawings. Those skilled in the relevant art will readily appreciate that these drawings and embodiments are merely illustrative and not intended to limit the true spirit and scope of the invention disclosed, taught and enabled herein.